An installation of this type, to supply under controlled pressure oxygen or air enriched in oxygen to the respiratory passages of a user is described in the document EP-A-347.282. Existing installations of this type are preferably complemented by an auxiliary outlet for a respiratory mixture under pressure to connect to a nebulization circuit introducing droplets of active product into the respiratory mixture during the inhalation phases:
It has been recently noted that nitric oxide, administered by inhalation, has pulmonary vaso-dilatory properties which can be quite useful for controlling symptoms of respiratory distress in adults and newborn or for maintaining the vital functions during surgical interventions in the heart-lung area. However, in the presence of oxygen, nitric oxide oxidizes rapidly to form nitrogen dioxide, which can lead to the formation of toxic metabolites.